Heretofore it has been proposed to provide a preformed outer covering and mount it on a metal core with the covering being manufactured at one location and then shipped to another location for application to a metal core with the covering being finish ground to provide the smooth outer surface required, after the covering is mounted on and permanently secured on the core. A printer's roller of such type is disclosed in U.S. Pat. No. 3,184,355 to James K. Brown. In this disclosure the inventor vulcanizes a sleeve of extruded rubber to a stretched knitted cotton fabric lining and this lining may be saturated with an adhesive for mounting on the core but the outer peripheral surface of the extruded rubber sleeve cannot be finish ground until the rubber is mounted on the core and permanently set.
The patentee emphasizes "the advantage of facilitating repair and maintaining of the roller at maximum operating efficiency at a location remote from the place of manufacture, with the consequent material savings of the time and cost of shipping the metal core back to the place of manufacture." This means that the extruded rubber sleeve, including its cotton fabric sleeve lining, after its manufacture on the "steel mandrel dimensioned substantially the same as the core" must be "stored or shipped for future use at any desired point." It necessarily follows that the extruded rubber sleeve is mounted on the metal core only at the point of use, after which it must be finish ground, on the core, to provide the smooth outer peripheral surface necessary to the proper functioning of the roller in such use.
The patentee states that his "outer covering 12" may be used immediately but does not suggest that this can be done at the point of manufacture which is contrary to the inventive concept disclosed. The extruded rubber covering can only be installed on the metal core at the point of use after removing an old covering and cleaning the core "preferably with sandpaper." It would be inconsistent with this disclosure to suppose that the rubber covering could be permanently mounted on the metal core at the point of manufacture and then incur the asserted penalty that "a considerable part of the costs comes from the expense and time required for transporting the rollers between manufacturing or repair centers and use locations" as pointed out initially in the patent as an object to reduce the cost to the user.
The relatively soft, non-rigid structure of the extruded rubber sleeve as vulcanized onto the knitted cotton fabric sleeve lining makes it necessary to finish grind the outer peripheral surface of the rubber only after it has been mounted on the metal core and allowed to permanently set. It is pointed out in the patent that the roller, after the inner fabric lining is thoroughly saturated with a suitable metal-fabric adhesive and the covering is slipped over a metal core while the adhesive is still wet, must be allowed to stand overnight for curing or setting of the adhesive to form an effective bond between the core and the covering. This involves a considerable loss of time at the point of use, especially in view of the fact that the roller must be "finish ground and polished in conventional manner, and the end portions of the outer covering 12 may readily be trimmed to conform to the end surfaces of the main part of the metal core." These facts all confirm the necessity for mounting and finishing the rubber covering at the point of use.
The inventor Brown also has U.S. Pat. No. 3,750,250 disclosing a printer's roller having a rubber sleeve but the concept here has to do with the manufacture of a lightweight roller complete with end journals and which eliminates the usual relatively heavy metal core to reduce the cost of the roller to the point where it becomes feasible for a user to discard an entire roller when the rubber becomes worn and requires maintenance. This appears to be the principal purpose of the invention and is described in the patent as being obtained by extruding a sleeve of rubber, or by casting the sleeve from an elastomer onto a long aluminum tube and then cut this tube, with the sleeve installed, into the required lengths to provide individual rollers that are completed by the mounting of journals in the ends of the individual lengths. These journals are stated to be injection molded in plastic and secured in the aluminum tube lengths by adhesive or by a press fit. The completed assembly is thereafter trued by finish grinding the outer peripheral surface of the sleeve and the ends trimmed to provide a complete roller said to be cheap enough to be thrown away when replacement becomes necessary.